Modeling of EPR Parameters for Cu(II): Application to the Selective Reduction of NOx Catalyzed by Cu-Zeolites
[EN] We present a combined theoretical-experimental study aiming to provide information about the location and coordination environment of the Cu2+ species involved in the selective reduction of NOx with NH3 catalyzed by Cu-zeolites. From the experimental side, we show and discuss the EPR spectra of the three molecular sieves most widely used as catalysts for the NH3-SCR-NOx reaction, namely Cu-SSZ-13, Cu-SAPO-34 and Cu-ZSM-5 both in their hydrated state and after dehydration. Then, we investigate the EPR spectra of Cu-SSZ-13 and Cu-SAPO-34 under the following conditions: (i) after NH3 adsorption, (ii) after NO addition, and (iii) in the presence of a NO/O-2 mixture. As regards the theoretical part, an exhaustive computational study has been performed that includes geometry optimization and calculation of the EPR parameters of all the relevant systems involved in the NH3-SCR-NOx reaction. The influence of local geometry and Al/Si distribution in the zeolite framework on the EPR parameters and the most probable location of Cu2+ in each material are analyzed, and assignations of the EPR signals obtained under different reaction conditions are discussed. ; This work has been supported by the Spanish Government through Severo Ochoa Program (SEV 2012-0267), MAT2015-71261-R and CTQ2015-68951-C3-1-R, and by the European Union through ERC-AdG-2014-671093 (SynCatMatch). Red Española de Supercomputación (RES) and Centre de Càlcul de la Universitat de Valencia are gratefully acknowledged for computational resources and technical support. E.F.V. thanks MINECO for her fellowship SVP-2013-068146. ; Fernández-Villanueva, E.; Moreno González, M.; Moliner Marin, M.; Blasco Lanzuela, T.; Boronat Zaragoza, M.; Corma Canós, A. (2018). Modeling of EPR Parameters for Cu(II): Application to the Selective Reduction of NOx Catalyzed by Cu-Zeolites. Topics in Catalysis. 61(9-11):810-832. https://doi.org/10.1007/s11244-018-0929-y ; S ; 810 ; 832 ; 61 ; 9-11 ; Chen H-Y (2014) In: Nova I, Tronconi E (eds) Urea-SCR technology for deNOx after ...